In a sequence of manufacturing a semiconductor device, there is a process of forming a nitride film such as a silicon nitride film (SiN film) or the like, serving as an insulating film, on a semiconductor wafer represented by a silicon wafer. A chemical vapor deposition (CVD) method is used for such a SiN film forming process.
When a trench is buried with a SiN film (CVD-SiN film) by the CVD method, voids or seams may occur. In this case, a method for etching-back up to the site where the voids or seams occurred and forming a SiN film again by the CVD method was used.
However, with a recent tendency to miniaturize devices, a step coverage in the CVD-SiN film is not sufficient. Thus, it becomes difficult to suppress the occurrence of voids or seams even by using the above method.
As a technique capable of forming a film with a step coverage better than that by the CVD method, an atomic layer deposition (ALD) method is known. This ALD method is used to bury a fine trench with a SiN film.
However, as devices become finer and finer, it becomes difficult to bury the fine trench with the SiN film while preventing the occurrence of voids or seams even by using the ALD method.